While it's so tempting to pick a character like Puddleglum, Reepicheep or even Jewel, I ultimately had to go with Aslan. There is so much wisdom and layered symbolism to be found in his words and actions in the Chronicles. His character and other characters' interactions with him are truly the best parts of the series, and he's the "glue" that holds all of the books together, if you will. He is a truly remarkable character; I've never seen anything like Aslan anywhere else in fiction.